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Ok Google: please publish your DKIM secret keys

blog.cryptographyengineering.com

11–20 of 492 posts

Re: Ok Google: please publish your DKIM secret keys

#11
post #4

Interesting/educational read but I'm still not convinced that this unintended side effect is a bad thing - it seems like a desirable property to have authenticated emails. Matt argues this might lead to regular folks (as opposed to politicians) getting blackmailed, but: 1) it seems unlikely this cryptographic proof is needed (he acknowledges this criticism in the post), and 2) what seems more likely to me is that pol…

You might want to validate your emails more than a few months out. Regardless of if your emails are valid or not, blackmail is still a crime. Not being able to have your emails validated doesn't protect you from blackmail. The power of blackmail is often in the social cost of the accusation itself. The thing that protects you from blackmail is not getting involved in things you can be blackmailed for. This is like sa…

> The thing that protects you from blackmail is not getting involved in things you can be blackmailed for.

This is incorrect, because the things that someone can be blackmailed for is not the same as the set of immoral or unethical acts. You can be blackmailed for being gay, or for having a serious medical condition that's undisclosed. Neither of those situations is a "well just don't do that" kind of thing.

The defense against blackmail is to make blackmail difficult (eg release DKIM keys), severely punish people who engage in blackmail, and guard your secrets effectively.

> This is like saying don't lock your doors so that nobody can break and enter into your house.

This is like saying the latch on your fence is a security mechanism. Nobody intended that fence latch to keep your safe or secure and hiding behind it won't make you safer. Rip away the false pretense.

Re: Ok Google: please publish your DKIM secret keys

#12
If Google did rotate the keys, it's quite likely some enterprising people would log observed keys. With access to a log of keys (that you don't believe has been tampered with) then rotating keys doesn't prevent non-repudation.

An alternative would be for email servers to strip the DKIM headers on inbound emails after recording that the email was validated. The email stored at rest then no longer provides non-repudation. Nothing is stopping you doing this today.

Re: Ok Google: please publish your DKIM secret keys

#13
post #4

Interesting/educational read but I'm still not convinced that this unintended side effect is a bad thing - it seems like a desirable property to have authenticated emails. Matt argues this might lead to regular folks (as opposed to politicians) getting blackmailed, but: 1) it seems unlikely this cryptographic proof is needed (he acknowledges this criticism in the post), and 2) what seems more likely to me is that pol…

You can authenticate messages in a way that only the recipient can verify (Diffie-Hellman plus MAC).

Re: Ok Google: please publish your DKIM secret keys

#15

If Google did rotate the keys, it's quite likely some enterprising people would log observed keys. With access to a log of keys (that you don't believe has been tampered with) then rotating keys doesn't prevent non-repudation. An alternative would be for email servers to strip the DKIM headers on inbound emails after recording that the email was validated. The email stored at rest then no longer provides non-repudati…

> rotating keys doesn't prevent non-repudation

That's why he says Google also needs to publish the private keys.

Re: Ok Google: please publish your DKIM secret keys

#17

If Google did rotate the keys, it's quite likely some enterprising people would log observed keys. With access to a log of keys (that you don't believe has been tampered with) then rotating keys doesn't prevent non-repudation. An alternative would be for email servers to strip the DKIM headers on inbound emails after recording that the email was validated. The email stored at rest then no longer provides non-repudati…

[deleted]

Re: Ok Google: please publish your DKIM secret keys

#18
So the author's central thesis essentially seems to boil down to that leaked emails were able to be cryptographically verified, because of DKIM and so we should prevent that so people can't use email to blackmail politicians? Ultimately I prefer the more information that we can get on politicians available.

It seems to me that especially when an elected official has something they don't want others to know about that it should be public knowledge.

After all an efficient marketplace only is efficient if all actors have access to as much information as possible.

EDIT: As a follow up, several people point out that it could happen to me or a family member, but this seems even further reason to have DKIM so that if someone attempts to blackmail me based on the contents of my email, checking the DKIM signature makes it even easier to disprove a bad blackmail attempt.

Re: Ok Google: please publish your DKIM secret keys

#19
post #4

Interesting/educational read but I'm still not convinced that this unintended side effect is a bad thing - it seems like a desirable property to have authenticated emails. Matt argues this might lead to regular folks (as opposed to politicians) getting blackmailed, but: 1) it seems unlikely this cryptographic proof is needed (he acknowledges this criticism in the post), and 2) what seems more likely to me is that pol…

You can authenticate messages in a way that only the recipient can verify (Diffie-Hellman plus MAC).

If you had access to a public key for every email address then why stop at authentication - you could encrypt all email on the web. But we don't, so we can't.

Re: Ok Google: please publish your DKIM secret keys

#20

I find it pretty funny that the author wrote this because they are salty that the leaked hunter Biden emails could be verified with DKIM

This is false. The article pointed to DKIM being used for journalistic verification for multiple parties (persons and organizations) across the political spectrum. It's not salty or overtly political.
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